WASHINGTON — A runaway military surveillance blimp that knocked out power for thousands when it dragged its severed tether across Maryland and Pennsylvania last year is still causing problems months later for its manufacturer, Waltham-based defense contractor Raytheon.
Citing the embarassing episode and other problems, lawmakers dealt Raytheon a blow this month by denying the latest funding request for the $3 billion program — leaving the system of unmanned blimps floating in limbo.
The pilot program, designed to detect incoming cruise missiles and other threats, involved two aerostats equipped with radar systems suspended thousands of feet in the air and tethered at Aberdeen Proving Ground in Maryland.
When one of the blimps broke loose last October and floated free for 150 miles, it captured national news attention and live coverage on cable networks. It finally came to rest in a field in Moreland Township, Pennsylvania.
Raytheon serves as prime contractor for the program, and some of the radar equipment on the aerostats is manufactured in Massachusetts. Raytheon declined to say where in Massachusetts the equipment is manufactured or whether discontinuation of the program would result in any job losses in the state.
A spokeswoman for Raytheon said the corporation believes the program should continue.
“Raytheon believes JLENS is a proven cruise-missile defense capability,” Raytheon spokeswoman Keri Connors wrote in an e-mail to the Globe.
But Maryland Senator Barbara Mikulski, the top Democrat on the Senate Appropriations Committee, which rejected a $27 million Army request to relaunch the blimps on March 9, said lawmakers are not convinced.
“I have very grave reservations about both the program’s safety for local communities and its national security accomplishments,” she said in a prepared statement. “We should get a lot more for our national security for $3 billion.”
The blimps are designed to detect missiles, drones, and planes, as well as ground vehicles and enemy boats.
The government approved a trial run for the program — the Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System, or JLENS — to monitor the airspace over Washington and determine if the system could alert US forces to incoming threats with enough time to respond.
Similar technology is used for surveillance at American bases in the Middle East.
In October, one of the aerostats became untethered. The cord supposed to anchor the blimp to the ground trailed the airship, leaving a scar across the landscape and knocking out power lines in its wake. Roughly 35,000 Pennsylvania residents lost power as a result.
The Pentagon conducted an investigation after the incident. Although the report is not public, the Los Angeles Times reported that an air pressure monitor in the aerostat malfunctioned, causing the blimp to turn and put unsustainable pressure on the inch thick tether. A device that should have automatically deflated the balloon before it drifted too far away did not deploy because it lacked batteries.
Mikulski said the review prompted her to favor shutting down the program.
“The investigation indicated a lack of training, supervision, and oversight,” she said. “I am really worried it could happen again.”
In January, an annual Department of Defense report found that the JLENS system had not been performing properly even before the October incident. It found the system incapable of reliably tracking “high priority” targets.
“System-level reliability, both software and hardware, is not meeting the program’s goals for reliability growth,” the report said.
The JLENS program garnered attention for failures in the past, as well. In April 2015, the system failed to detect a protester who flew a gyrocopter through restricted airspace onto the Capitol lawn. And in 2010, a JLENS aerostat in North Carolina was destroyed in a storm.
Raytheon tried to persuade lawmakers on the Senate Appropriations Committee to save the program. But in a letter earlier this month, Mississippi Senator Thad Cochran, who serves as the Republican chairman of the Senate Defense Appropriations Subcommittee, and Illinois Senator Dick Durbin, the top Democrat on the subcommittee, denied the Army’s request for funding to restart the program this year.
The program was suspended last October following the runaway blimp incident.
Ben Marter, a spokesman for Durbin, called the JLENS program a “big disappointment to taxpayers with a $3 billion price tag.” The trial program in Maryland was supposed to prove JLENS’ reliability so it could be expanded.
“It failed spectacularly,” Marter said.
The Senate’s rejection of funds means the project remains suspended through at least the end of fiscal year 2016, in September.
The White House’s proposed FY2017 budget requests over $45 million to continue funding the program, but the opposition from key senators overseeing appropriations indicates lawmakers are unlikely to provide the money.
“There’s been broad concern in the committee about the pace of the program,” said Chris Gallegos, a spokesman for the Senate Appropriations Committee.
“When the balloon became untethered, that highlighted the concerns that they had.”